Behaviour issues

I need help with how I can help my boy. He is a very energetic little boy, however he absolutely hates groups of people, even family he will get extremely overwhelmed and cry until I sit in a room alone with him, despite seeing them individually regularly. He also hates anything touching him such as wet/dirty hands and once doing a poo if I’m not quick enough in changing him, he will take everything off and then smear it everywhere and cry saying yuk or dirt. I’m just looking for some advice of how I can stop this and help him feel more comfortable around bigger groups of people. TIA x